1. Field of the Invention
The present invention relates to medical catheters and to peritoneal dialysis catheters in particular.
2. Background Information
The foldable peritoneal dialysis catheter as disclosed in U.S. Pat. No. 5,322,519 (“the Ash catheter”) represented a substantial advance in peritoneal catheter design and technology. However, the design of the ash catheter leaves certain characteristics of the ideal peritoneal dialysis catheter lacking.
The only feasible embodiments of the Ash catheter invention are those designed for inflow or outflow, but not both. Ash does teach the basic concept of a peritoneal dialysis catheter for continuous use (Column 4, lines 54 et seq.), in other words, one which includes separate conduits for simultaneous inflow and outflow. However, Ash fails to provide an actual, workable design.
Ash's FIG. 4 depicts a proposed design for a continuous use peritoneal catheter, but one which simply cannot be made when existing technology is applied to the silicone material from which such catheters must be made. For example, Ash's septum 128 must, in order to be operative, form a fluid seal with the inner wall of housing 122. Even if this were possible to achieve in the manufacturing process (which experts in the silicone extrusion and manufacturing industry indicate it is not), the resulting catheter would be too rigid (because of the added rigidity of such 128) to be suitable for implantation. In addition, the T-configuration shown for this embodiment would, in actual application, cause accumulation of biological debris (and ultimately clogging) at the 90 degree bends in the conduits. In addition the “double D” cross section configuration proposed by the Ash patent further precludes necessary catheter function. Such a cross section will occlude due to fiber at the 90 degree joint of the “T” junction.
Ash's alternative continuous dialysis catheter design (shown in Ash's FIG. 8) is also a non-viable design suggestion. Merely conjoining two parallel conduits (Ash's “plenum chambers” 146 and 148) creates a cross-sectional footprint (other than substantially circular) which is not suitable for passage through, and long-term residence in the abdominal wall because of increased propensity for leakage, bacterial invasion, etc.
It would well serve those who administer and those who receive peritoneal dialysis to provide a viable design for a continuous use peritoneal dialysis catheter—one which provides all the benefits of the viable embodiments of the Ash single direction flow catheter, but goes farther in satisfying the remaining, unfulfilled objectives for an Ash-like catheter for continuous dialysis use.